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Author: Dr. Haresh Shah, Stanford University and Risk Management Solutions Inc. Source: hazards@lists.colorado.edu, 14 October 1995
	Scientific Profiles of the Big One keywords: risk estimation, urbanization
Globally, earthquake risk is increasing due to massive urbanization andthe use of less-than- desirable sites within urban regions. The evolutionof megacities has put a tremendous strain on our ability to deal withnatural catastrophes. The January 17, 1995, Great Hanshin (Kobe) earthquake provided us with clear evidence of the extensive damagepossible from earthquakes and the vulnerability of highly complex urbanregions.For complex, and at times seemingly unmanageable, mega-urban regions, itis important to develop an estimate of the physical and economic impactsof very large earthquakes. It is not clear if Kobe would have betterwithstood the quake if the city had a prior estimate of what could happento its lifelines, residential and commercial properties, economy, andcitizens' well-being. However, the greatest risks (old residentialconstruction, areas of potential liquefaction along the waterfront, weaklinks in the highway and railway systems) probably could have beenidentified and mitigating actions taken. To betterunderstand the potential impacts on megacities, RMS, Inc. and Stanford University have developed scenarios for large earthquakes in SanFrancisco, Los Angeles, and Tokyo.   Context of These Studies In these three studies, all analyses werebased on the general vulnerability of various classes of construction ofbuildings, lifelines, and other structures. No specific sites orstructures were inspected. Any special safeguards made by specificbuilders, utility companies, and others to mitigate the effects of anearthquake were not known by the study team and hence not taken intoaccount. Hence, the results of these studies are intended to provide onlya broad picture of the impact of a major earthquake. In spite of these uncertainties, these studies provide an importantcontribution to urban communities in seismically active regions. Theresearchers welcome comments from readers to improve our ability todevelop such complex scenarios.   The Increasing Nature of Global Earthquake Risk Again, the interaction between society, structures, and nature is suchthat world earthquake risk is increasing. Risk is a function of fourparameters: Hazardis what nature does to humans, e.g., earthquake occurrence,and remains relatively constant from year to year. Locationrefers to the siting of structures and buildings. Good siteshave become scarce and less desirable sites are increasingly being used. Exposureis also increasing. More population, buildings, andinfrastructure results in a higher exposure to earthquake risk. Vulnerabilityis a function of the quality of construction.